Propagate extra fields form group into WorkSpecifications

Add extra fields in groups to propagate to underlying WorkSpecifications.

It consists of the same filters and predecessor_specification fields from the WorkSpecifications and reuses the templates already available from the WorkSpecification.

A small change has been made to the filters_preprocessory.py to add an argument to only show certain fields (supplying None shows all fields). This is to accommodate the fact that the obs_idfilter is not used inGroup`s as it's already present and should be handled differently.

Closes SDC-922